RSS
Print pageHome » Partial discharges, condition monitoring
Partial discharges, condition monitoring
Q: Considering partial discharges related to condition monitoring in electrical equipment: On which type of equipment is this technology applied?; What are the parameters monitored?; What are the equipments/sensors used to monitor partial discharges?; What about indicators/statistics of that monitoring?
A: It is uncommon to see significant partial discharge (PD) activity in machines rated below 6 kV. For that reason, PD monitoring is usually confined to machines (electric motors and generators) rated 7 kV or higher.
Partial discharge monitoring instrumentation takes several forms. Ozone detection has a drawback: it does not detect PD activity within sealed voids in the coils. Ozone levels can also be influenced by the machine enclosure. More airflow through the machine will reduce ozone levels as compared to a machine with the same PD activity but 'stagnant' airflow.
Direct PD monitoring can be done with instrumentation that detects the actual discharges. Companies who produce this equipment include Iris Power Engineering, Doble, and Adwel. PD activity can be monitored on-line ("live") at the terminal box or inside the machine enclosure. The instrumentation will report higher values (i.e., more incidents) of PD activity when measuring activity inside the machine enclosure, so comparing PD activity detected within the enclosure of one machine to that inside the terminal box of another machine, is misleading. Consistency in location of PD monitoring equipment is helpful for consistent results and realistic comparisons of different machines.
Winding condition can also be evaluated for PD activity, when the machine is out of service, using instrumentation also available from the above-mentioned companies.
One word of caution: The PD activity may vary considerably for machines of different ratings/manufacturer, so direct comparison to identical motors is most meaningful. Work with the vendor you select; they have extensive databases to help you interpret the PD results.
Here are more of the latest questions on: Motors Drives
How do you calculate the force of a moving fluid against an obstruction?
What is the torque required for motor selection? We have a water tank that is 4 ft. high, 2 ft. wide, 12 ft. long. The tank is divided vertically in two parts by a sheet. There is a gap of two feet on both ends of the tank separation plate. We want to install a paddle wheel of radius two feet on one gap. When it rotates the water it will be pushed to the bottom portion and will come out from the gap on the other side. How much torque will be required to rotate the paddle wheel if the blade size is 2 ft. by 2 ft. each and 3 blades will be in contact with water at the same time. The rpm required is 70.
How do you calculate torque requirements for a paddle wheel used to move water in a pond?
How do you calculate torque requirements for a paddle wheel used to move water in a pond? I need to know torque in order to size a motor and gear reducer for a paddle wheel.
How can I avoid smoking the motor at startup?
I have a 12.25-inch disk when loaded with components equals about 8 pounds. Others in the same field have a problem of smoking the motor during startup. I want to run at a variable speed to 3600 rpm.
It is important to keep the motor as small as possible, and long life and extremely low maintenance are important.
How can we increase the speed of an electric motor?
How can we increase the speed of an electric motor by a VFD system supplying energy to a pump? Suppose the motor power is sufficient enough to prevent overloading the motor?
What would be the power of 2950 rpm-VFD drive to yield 3650 rpm 90 kW output?
I need to supply 90 kW power and 3650 rpm for running a pump. The highest available electric motor would be 2950 rpm. I have to use a variable frequency drive (VFD)-motor system for raising the speed. What would be the power of 2950 rpm-VFD drive to yield 3650 rpm 90 kW output for the pump?
